Effect of CMK Composite Micro-powder on Corrosion Resistance and Impedance Spectrum of Concrete

Purposes On the basis of the engineering situation of saline soil in the middle and south of Shanxi province and the characteristics of coal-series metakaolin (CMK), the influeace of the soil on the corrosion-resistance and impedance spectrum of concrete was studied. Methods The corrosion-resistant concrete was prepared by using different amount of CMK and equal amount of fly ash as composite micropowder. The corrosion environment of saline soil and groundwater was simulated by dry-wet cycle sulfate corrosion solution. The corrosion resistance coefficient of concrete compressive strength and electrochemical impedance spectroscopy were taken as the corrosion resistance indexes, and the influence mechanism and law of different content of CMK on the corrosion resistance of concrete were studied. Findings The results show that the corrosion resistance of concrete can be improved by using CMK composite micropowder, and the concrete with 5% CMK and fly ash can meet the requirement of KS150. The corrosion resistance of 10% metakaolin and fly ash is the best, and the sulfate resistance is above KS150. The resistance of the electrolytes in pore solution of concrete system in corrosive environment, the Rs of the charge transfer reaction of free electrons in C-S-H gel are negatively correlated with the porosity of concrete, that means as the porosity of concrete increases, both Rs and Rct decrease. Electrochemical impedance spectros-copy can provide a new method and idea for nondestructive testing of corrosion-resistant concrete.